Long vertical runs of wire must be supported with how often?

The correct answer is based on electrical installation practices which stipulate how often wires must be supported to ensure safety and compliance with code requirements. Long vertical runs of wire need to be supported every 100 feet to prevent sagging and potential damage to the wire insulation. This is important as unsupported wire can create stress points or wear over time, leading to electrical faults or hazards. The regulation ensures that wires maintain their structural integrity and remain clearly within guidelines set by industry standards, thereby enhancing the overall safety of the installation. The 100-foot rule strikes a practical balance between support frequency and ease of installation.